/*这是一个将回声客户端传输的字符串按序保存在文件中的回声服务器*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#define BUF_SIZE 30

void read_childproc(int sig);

int main(int argc, char **argv)
{
    int serv_sock, clnt_sock;
    sockaddr_in serv_adr, clnt_adr;
    int fds[2];
    int str_len;
    int state;
    pid_t pid;
    struct sigaction act;
    act.sa_handler = read_childproc;
    sigemptyset(&act.sa_mask);
    act.sa_flags = 0;
    state = sigaction(SIGCHLD, &act, 0);
    socklen_t adr_sz;

    char buf[BUF_SIZE];
    if (argc != 2)
    {
        printf("Usage : %s <port> \n", argv[0]);
        exit(1);
    }

    serv_sock = socket(AF_INET, SOCK_STREAM, 0);
    memset(&serv_adr, 0, sizeof(serv_adr));
    serv_adr.sin_family = AF_INET;
    serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_adr.sin_port = htons(atoi(argv[1]));

    bind(serv_sock, (sockaddr *)&serv_adr, sizeof(serv_adr));
    listen(serv_sock, 5);

    pipe(fds);
    pid = fork();
    if (pid == 0)
    {
        FILE *fp = fopen("echomsg.txt", "wt");
        char msgbuf[BUF_SIZE];
        int i, len;
        for (i = 0; i < 10; i++)
        {
            len = read(fds[0], msgbuf, BUF_SIZE);
            fwrite((void *)msgbuf, 1, len, fp);
        }
        fclose(fp);
        return 0;
    }
    while (1)
    {
        adr_sz = sizeof(clnt_adr);
        clnt_sock = accept(serv_sock, (sockaddr *)&clnt_adr, &adr_sz);
        if (clnt_sock == -1)
        {
            continue;
        }
        else
        {
            printf("客户端来了...\n");
            pid = fork();
            if (pid > 0)
            {
                close(clnt_sock);
            }
            else if (pid == 0)
            {
                close(serv_sock);
                while ((str_len = read(clnt_sock, buf, BUF_SIZE)) != 0)
                {
                    write(clnt_sock, buf, str_len);
                    write(fds[1], buf, str_len);
                }
                close(clnt_sock);
                puts("客户端关闭...");
                return 0;
            }
        }
    }
    close(serv_sock);
    return 0;
}

void read_childproc(int sig)
{
    pid_t pid;
    int status;
    pid = waitpid(-1, &status, WNOHANG);
    printf("子进程已经移除：%d，返回值是：%d\n", pid, WEXITSTATUS(status));
}